1. Field of the Invention
The present invention relates to a radiographic imaging system and an access controller for communication access. More particularly, the present invention relates to a radiographic imaging system and an access controller for communication access, in which radio communication is used, and communication errors or delay due to radio interference in wireless communication connection can be prevented.
2. Description Related to the Prior Art
An X-ray imaging system or radiographic imaging system is widely used in medical diagnosis in a hospital. The X-ray imaging system includes an X-ray source apparatus or radiation source apparatus, and an X-ray imaging apparatus or radiographic imaging apparatus. The X-ray source apparatus generates X-rays. The X-ray imaging apparatus forms an X-ray image or radiation image of a body of a patient by receiving X-rays transmitted through the body. The X-ray source apparatus includes an X-ray source, a source driver (controllable) and a start switch. The X-ray source applies X-rays to the body. The source driver drives and controls the X-ray source. The start switch inputs a command signal to the source driver to turn on the X-ray source. The X-ray imaging apparatus includes an X-ray image detector or radiation image detector, and a console unit, which receives a command signal for the X-ray image detector and the X-ray image from the X-ray image detector, and displays the X-ray image.
The X-ray image detector has a sensor panel or a flat panel detector (FPD), and detects the X-ray image by converting X-rays transmitted though a body into an electric signal. The X-ray image detector transmits the X-ray image immediately to the console unit which operates for displaying an image visibly. The use of the X-ray image detector is highly advantageous over radiography with an X-ray film or IP cassette (imaging plate cassette), because the image can be checked shortly after the imaging.
Examples of X-ray image detectors include a stationary type installed in an examination room, and a portable type, which is an electronic cassette having a portable housing and the sensor panel contained in the portable housing. The electronic cassette is usable in a state fixedly positioned on a floor stand or the like in the examination room for imaging the body in an erect posture or supine posture. Also, the electronic cassette is useful in X-ray imaging of in-patient care in which an operator goes to a hospital room of a patient of limited mobility, namely in a condition without possibility of moving to the examination room.
JP-A 2012-034936 discloses the X-ray imaging apparatus of a type of wireless communication connection between the electronic cassette and the console unit for transmitting data including the X-ray image. There are various modes of positioning the electronic cassette according to body parts of interest in the body. The electronic cassette may be disposed between the body and a bed, or may be held by hands of the patient. It is unnecessary to connect a cable to the electronic cassette by use of the wireless communication connection, so that the positioning of the electronic cassette can be freely carried out without consideration of a path of the cable. However, attenuation of radio waves may be more remarkable assuming that a relative position of the electronic cassette changes according to a distance or direction of the electronic cassette relative to the console unit with changes of the posture and position. Communication quality cannot be stably maintained due to frequent occurrence of communication errors or delay. In view of this, the X-ray imaging apparatus of JP-A 2012-034936 finely changes an output of the communication according to changes in the relative position between the electronic cassette and the console unit, to maintain communication quality stably.
Also, JP-A 2005-253627 discloses a method of ensuring communication quality of an X-ray imaging apparatus in a stable form in a manner similar to JP-A 2012-034936. In a computed tomography apparatus (CT apparatus) of X-rays, there are an image detector for detecting an X-ray image and an image receiver for receiving the X-ray image from the image detector. A radio communication between the image detector and the image receiver is performed with a plural radio communication channels in a multi-channel form. Assuming that failure such as circuit breakage is detected in a first one of the radio communication channels, the radio communication is changed over to a second one of those operable normally.
The ideas of JP-A 2012-034936 and 2005-253627 for ensuring communication quality are technically important in the field of the X-ray imaging apparatus in consideration of effectively preventing communication errors and delay. According to a research of the medical diagnosis in hospitals, the number of imaging requests for the in-patient care is 20 per day in one hospital facility, and may be increased by 30 as additional urgent requests due to the progress of numerous patients. Only one technician or operator frequently works for imaging in the in-patient care. Thus, a task of 50 or more imaging requests must be performed only by himself or herself in a day. In general, each one event of imaging of the imaging request takes about 5 minutes. The in-patient care is for the purpose of care for patients of limited mobility. Positioning of the body of the patient by an operator for a proper posture of his or her upper body requires much time in relation to a position of the electronic cassette. Thus, the importance of ensuring communication quality of data in a stable manner is considerably high in the severely restricted condition of the medical diagnosis in the hospital facility.
However, new problems have been found recently in relation to the imaging in the in-patient care. Communication quality of data in a stable manner cannot be ensured only by the techniques suggested in JP-A 2012-034936 and 2005-253627.
Introduction of radio network nodes (radio communication devices) has been made recently in medical facilities in a manner similar to general use. The X-ray imaging apparatus and other medical apparatus with a radio network node have been used widely. A portable terminal device of radio communication is a typical example for viewing a medical chart or inputting information in electronic data of diagnostic information. However, available bands of frequency of radio waves is limited. Frequency overlap may occur to create radio interference in case a radio communication channel of an equal frequency is used by a plurality of radio network nodes. The radio interference causes communication errors and delay. As the number of radio communication channels is limited, it is impossible to assign all radio network nodes with radio communication channels of different frequencies without creating radio interference.
The X-ray imaging apparatus is moved from room to room in a hospital facility for the purpose of the in-patient care. Communication environment of the X-ray imaging apparatus is changeable with places and time. Positions and numbers of medical service providers (physicians and nurses) carrying portable terminal devices of radio communication are changed according to the hospital rooms and time. The problem of the radio interference cannot be resolved in the in-patient care even with a countermeasure for preventing radio interference in a limited place. The problem of the radio interference becomes more conspicuous according to an increase in the number of the portable terminal devices. The use of the portable terminal devices will be enlarged in future so as to make the problem more serious. In general, a data size of an X-ray image is large among various data for medical use. The problem must be coped with because of a loss in time due to the radio interference with communication errors or delay.
Search has been made by sampling and interviewing plural operators in the field of radiology. In addition to the problem of much time required for positioning of a body of a patient, manual handling of the electronic cassette is considerably laborious due to its large weight in comparison with an X-ray film, IP cassette or the like in the course of supporting the body of the limited mobility. Furthermore, required efficiency in working in a condition of restriction of the time is combined with muscle fatigue of each operator, to cause serious increase in mental stress. Accordingly, communication errors or delay even with a short period causes a problem of lowering the efficiency of the operator because of loss of time and the like. Solution of the above-described problem of communication errors or delay is essentially important in the field of medical diagnosis.
JP-A 2012-034936 and 2005-253627 do not mention those problems. The techniques disclosed in the documents are related to communication errors or delay due to internal factors in the X-ray imaging apparatus. No solution has been known for problems of communication errors or delay due to radio interference of the X-ray imaging apparatus with other radio network node or the like due to external factors of the X-ray imaging apparatus.